The cosmological evolution of colour gradients in spheroids

The analysis of the four-colour maps of galaxies in the Hubble Deep Field (HDF) has revealed, in the sample of 0.4< z <1 early-type field galaxies, the existence of ellipticals with a predominantly old coeval stellar population. However, there is another, unexpected, category of HDF early-type galaxies, in which the galaxy core is significantly bluer than the outer regions. We demonstrate that these colour gradients are predicted by the multizone chemodynamical model for the evolution of elliptical galaxies.
We suggest that the colour gradient could be used as a chronometer for the evolution of elliptical galaxies: galaxies younger than a few Gyr exhibit cores bluer than the surrounding galaxy as a result of ongoing star formation, while more evolved galaxies have redder cores because of metallicity gradients increasing toward the centre.     

电子航道图与航标遥测监控系统

“数字航道”建设的主要目标在于应用信息技术平台保障航道安全、提高航务管理水平。作为航道管理中的重要导航设施航标灯(船),对其工作状态、空间位置进行远距离全天候监测与遥控是\     

A simple population synthesis model for the continuum of the Seyfert type-2 galaxy Mk 348

The spectral energy distribution of the Seyfert type-2 galaxy Mk 348 is analyzed based on IUE observations and published data. It is found that most of the optical and near-IR flux comes from the underlying galaxy bulge population. The rest of the emission can be fitted by a power law of the formF _v v ^– with =0.6. In order to explain the X-ray emission this power law requires either a change of slope or a cutoff before 2 keV. The possibility that the emission originates in a young star cluster is discussed and a simple population synthesis model for the continuum of the galaxy is presented.     

Stellar indices and kinematics in Seyfert 1 nuclei

We present spectra of six type 1 and two type 2 Seyfert galaxies, a starburst galaxy and a compact narrow-line radio galaxy, taken in two spectral ranges centred around the near-infrared Ca  ii triplet (∼8600 Å), and the Mgb stellar feature at 5180 Å. We measured the equivalent widths (EWs) of these features and the Fe₅₂ and Fe₅₃ spectral indices.
We found that the strength of the infrared Ca  ii triplet (CaT) in type 1 Seyfert galaxies with prominent central point sources is larger than what would be expected from the observed strength of the blue indices. This could be explained by the presence of red supergiants in the nuclei of Seyfert 1 galaxies. On the other hand, the blue indices of these galaxies could also be diluted by the strong Fe  ii multiplets that can be seen in their spectra.
We have also measured the stellar‐ and gas-velocity dispersions of the galaxies in the sample. The stellar velocity dispersions were measured using both the Mgb and CaT stellar features. The velocity dispersion of the gas in the narrow-line region (NLR) was measured using the strong emission lines [O  iii ] λλ 5007, 4959 and [S  iii ] λ 9069. We compare the gas- and star-velocity dispersions and find that the magnitudes of both are correlated in Seyfert galaxies.
Most of the Seyfert 1 galaxies that we observe have stellar‐velocity dispersions somewhat greater than that of the gas in the NLR.     

闽江河口藨草湿地CH_4排放特征

用静态箱法,在2007年阴历每月(除2月和4月外)的初三或初四以及2007年7月12～13日(生长季)和12月16～17日(非生长季),分别采集闽江河口鳝鱼滩藨草(Scirpus triqueter)湿地的气体样品,利用GC-2010气相色谱仪分析样品的CH4浓度,并计算CH4排放通量.结果表明,10个月中,藨草湿地CH4排放通量涨潮前和落潮后的最大值分别出现在7月和8月,最小值分别出现在3月和1月;涨潮前和落潮后CH4排放通量变化范围分别为0.39～9.08 mg/(m2·h)和0.95～12.78 mg/(m2·h);各观测月藨草湿地涨潮前和落潮后CH4排放通量与距地表1 m气温和20 cm土温有显著的正相关关系(n=10, p<0.01),此外,涨潮前各观测月藨草湿地CH4排放通量与盐度显著负相关(n=10, p<0.05),与土壤含水量显著正相关(n=10, p<0.05);夜间的CH4排放通量总体低于白天;生长季和非生长季日变化观测中,各观测时刻藨草湿地CH4排放通量的变化范围分别为2.43～12.66 mg/(m2·h)和0.09～1.30 mg/(m2·h),潮汐是影响CH4排放通量日变化的主要因子.     

Precision abundance analysis of bright H ii galaxies

We present high signal-to-noise ratio spectrophotometric observations of seven luminous H  ii galaxies. The observations have been made with the use of a double-arm spectrograph which provides spectra with a wide wavelength coverage, from 3400 to 10 400 Å free of second-order effects, of exactly the same region as that of a given galaxy. These observations are analysed applying a methodology designed to obtain accurate elemental abundances of oxygen, sulphur, nitrogen, neon, argon and iron in the ionized gas. Four electron temperatures and one electron density are derived from the observed forbidden line ratios using the five-level atom approximation. For our best objects, errors of 1 per cent in t _e([O  iii ]), 3 per cent in t _e([O  ii ]) and 5 per cent in t _e([S  iii ]) are achieved with a resulting accuracy of 7 per cent in total oxygen abundances, O/H.
The ionization structure of the nebulae can be mapped by the theoretical oxygen and sulphur ionic ratios, on the one side, and the corresponding observed emission line ratios, on the other – the η and η' plots. The combination of both is shown to provide a means to test photoionization model sequences presently applied to derive elemental abundances in H  ii galaxies.     

多源空间数据库的设计与实现

随着全球环境的进一步恶化,各国政府越来越重视环境资源问题。我国已经投入大量人力物力完成了各类工程项目和相关的研究工作,积累了大量的环境资源数据,如何科学有效地利用这些数据,是我们面临的现实问题。空间数据库是在数据库技术基础上发展起来的。利用多源空间数据库进行存储与管理,正逐步应用到城市规划、土地管理等领域。本文阐述了多...     

鄂尔多斯东北部中侏罗世孢粉化石及古气候意义

鄂尔多斯盆地东北部内蒙古伊金霍洛旗乌兰木伦地区是我国重要的能源矿产地,含煤岩系赋存在侏罗系延安组中,延安组岩石组合以灰白色砂岩、灰色粉砂岩、灰色泥岩为主,夹多层煤层;延安组上覆直罗组以灰色、灰绿色砂岩、灰色粉砂岩、紫红色泥岩为主。通过对乌兰木伦地区武家塔露天煤矿剖面延安组和直罗组孢粉化石分析,在延安组中识别出Cyathidites-Lycopodiumsporites-Neoraistrickia-Cycadopites孢粉组合带,以桫椤科、石松科孢子繁盛,紫萁科孢子和单沟/原始沟类、松柏类两气囊花粉发育,卷柏科孢子及柏科花粉较常见为主要特征,时代为中侏罗世早期(阿林期—巴柔期)。根据延安组孢粉母体植物的生态环境分析,本区在这一沉积时期的气候属于温暖湿润的亚热带—温带型气候。直罗组孢粉化石较少,主要见Cyathidites minor,Osmundacidites parvus,Concentrisporites fragilis,Cycadopites spp.等。综合地层岩性、孢粉组合及古植被分析,延安组到直罗组沉积时期总体上呈现从温暖湿润的亚热带—温带型向半干旱—干旱炎热型的气候...     

泥质页岩-粉质黏土土石混合填料原位水平推剪试验研究

土石混合料是由土和岩块（碎石）组成的复合体。混合料中土的种类不同,岩块的种类及含量不同,剪切破坏特征亦不同。由于对其剪切破坏机理研究还不够深入,在工程中难以确定这类填料的强度参数。为进一步探明土石混合填料的剪切破坏特征,对泥质页岩-粉质黏土混合填料进行了12个原位大型水平推剪试验,根据现场试验结果,将这类土石混合填料的水平推力-位移曲线划分为5个阶段,并对各个剪切破坏面进行三维还原,为土石混合体内部破坏机理的进一步研究奠定了基础。